float tms_to_jd (struct tm *tms)
{
float month = tms->tm_mon + 1;
float a = (14 - month)/12;
float y = (1900+tms->tm_year)+4800-a;
float m = month + 12*a - 3;
float day = tms->tm_mday;

float jd = day + (153*m+2)/5 + y*365 + y/4 - y/100 + y/400 - 32045;

// The julian day begins at noon
jd -= 0.5;
return jd + (tms->tm_hour + (tms->tm_min + tms->tm_sec/60.0)/60.0)/24.0;
}

float tms_to_mjd (struct tm *tms)
{
return tms_to_jd (tms) - 2400000.5;
}